You would be better served by employing better light control in the viewing space instead of suffering over a replacement HDTV that happens to have the desired matte screen, but worse PQ than the model you have currently. By controlling the ambient light in the room you can pick and choose from the vast majority of HDTVs makes/models, including plasma, which offers better handling of fast motion and offers better black levels & contrast. Price will be better too for the same size panel.
I also suggest you do not use badly constructed viewing spaces like Costco or Sam's Club to evaluate PQ of various HDTV models. Go out of the way to find dedicated Home Theater stores that at least provides a semblance of a space for looking at HDTVs. Use sites like Amazon & AVS forum and read the user reviews of any particular HDTV you are interested in based on what you see in the HT store and Costco.
If the following model is what you are looking at, I would be inclined to choose it over the Sharp you mentioned.
Discussion of the 6100 series @ AVS-
I'm looking for a large "smart" LEDTV with a Matte screen for my bright 15' x 12' living room to replace a 32" Samsung LCD which I loved. I don't need 3D but I watch a lot of sports. I was disappointed that the LGs this year have glossy screens. I was looking at the Samsung 55E6150 and the SharpLC 60C847OU since it doesn't come in 55". I am a bit concerned the 60" is too big for the room. Also, I have not been able to discern picture quality because in Costco the pics running on the Sharp TV were cartoons and in BB it was connected to a game. I know that Sharp historically was not a leader in PQ. Can anyone help?